export default class PageView extends Component {
  state = {
    contents: [],
    contentsLen: 0
  }
  add = () => {
    this.setState(prev => {
      const cot = prev.contents.slice()
      cot.push({ text: 'hello world' })
      return {
        contents: cot,
        contentsLen: cot.length
      }
    })
  }
  remove = () => {
    this.setState(prev => {
      const cot = prev.contents.slice()
      cot.pop()
      return {
        contents: cot,
        contentsLen: cot.length
      }
    })
  }
  render () {
    return (
      <View className='container'>
        {this.state.contents.map((item, index) => (
          <Text key={index}>{item.text}</Text>
        ))}
        <Button className='btn-max-w button_style' plain type='default' onClick={this.add}>add line</Button>
        <Button className='btn-max-w button_style' plain type='default' disabled={this.state.contentsLen ? false : true} onClick={this.remove}>remove line</Button>
      </View>
    )
  }
}